Rocks & Minerals
- Igneous Rock is formed when magma cools.
Under The Ground:
- When Heated it becomes metamorphic rock.
- It can be melted again to form a new magma.
- When weathered and eroded it becomes sedimentary rock!
Formed when sediments compact into layers.
Inside The Earth:
- Can be heated under pressure to form metamorphic rock.
- It can be weather AGAIN to form new sediment!
Formed when rock changes under heat & pressure!
Inside The Earth:
- Can melt to form magma
- Weather & Erode to Form Sediment
Ways To Identify Different Minerals:
Most easily observed but the least useful!
Some minerals have a similar color, this is why it is least useful!
Luster is the way a mineral shines in reflected light.
There are several terms used to describe nonmetallic luster. Examples could be virtuous, like quartz or gypsum which is pearly.
The streak of a mineral is the color of its powder when rubbed on a white tile.
Example a yellow rock has a green streak.
Streak color rarely varies!
The cleavage of a mineral is its ability to split easily or separate along flat surfaces. Cleavage can even be observed on tiny mineral grains. This is a very useful property unlike color!
Example: Mica splits into thin sheets.
Minerals that don't split have things called fracture.
The hardness of a mineral is its resistance to be scratched.
Example: Diamond is the hardest mineral and talc is softest.
Friedrich Mohs created a hardness scale. The minerals are sorted from a 1-10 scale.
Crystal shape can be a useful property identifying minerals and if they had time and space to form crystals.
Acid Test is testing if the mineral erodes when dropping certain liquid acids on it.
Test if the mineral can bend or mold into different shapes
See if the mineral is magnetic (Iron)
Glows in the dark!
Taste for minerals such as salt or Halite!